It is known that naphthoquinones have various medicinal effects. For example, among naphthoquinones, (−)-2-(1-hydroxyethyl)-5-hydroxynaphtho[2,3-b]furane-4,9-dione, also referred to as NQ801 hereinafter, of the following formula:
is an optically active compound comprised in Bignoniaceae Tabebuia, Taheebo, including Tabebuia avellanedae; Tabebuia impetiginosa, etc., and is known to have the anticancer activity (see Patent Document 1 and Nonpatent Document 1). Some methods for synthesizing NQ801 are known, and for example, include the following scheme (see Patent Documents 2 and 3):

In the methods of both Patent Documents, 5-hydroxynaphtho[2,3-b]furane-4,9-dione (3) which is synthesized from 2-dimethylamino-5-hydroxynaphthalene-1,4-dione (1) derived from easily available 5-hydroxynaphthalene-1,4-dione, also referred to as juglone hereinafter, is used as a key intermediate. In the above methods, nonnegligible amounts of by-product (3′) are obtained in a step wherein the key intermediate (3) is synthesized from the above compound (2), and it is not easy to separate the by-product from the compound (3).

In the method of Patent Document 2, it is required that the desired compound (3) is reduced by a base, and then the resulting racemate (4) of NQ801 is optically resolved. In the method of Patent Document 3, the number of synthetic steps is reduced by an asymmetric synthesis compared to the method of Patent Document 2, but a problem which the compound (3) has to be separated from the by-product (3′) produced in the synthesis still remains.
On the other hand, it is known that naphthopyrrole-diones are synthesized by the conventional Sonogashira coupling reaction using the similar substrate to the above compound (1) like the following scheme (see Nonpatent Document 2):

However, the method of the above literature wherein the substituent R of benzene ring is low reactive and comparatively stable chemical group is specific to the substrate. Since the alkyne is required to be treated in a ring-closure reaction in other step after the coupling reaction in the synthesis of naphthopyrrole-diones in the above method, a problem in view of the number of synthetic steps remains.
Furthermore, the following reaction is known as the coupling reaction of naphthoquinones and alkynes (see Nonpatent Document 3):

In the method of Nonpatent Document 3, two types of naphthofuranediones are nonselectively obtained and no methods wherein either one of naphthofuranediones may be selectively prepared are disclosed.

It is considered that hydroxyl group on 2-position of the naphthoquinone ring of the reaction substrate largely involves in the reaction disclosed in the literature.
Nonpatent Document 4 also discloses similar coupling reactions to the above, however, no reaction examples wherein a reaction substrate having hydroxyl group on 5-position of the naphthoquinone ring is used are disclosed.
[Patent Document 1] JP2669762
[Patent Document 2] JP-A-2006-290871
[Patent Document 3] JP4077863
[Nonpatent Document 1] Shinichi U E D A, et al., Phytochemistry (1994), Vol. 36, No. 2, p. 323-325
[Nonpatent Document 2] Mark S. Shvartsberg, et al., Tetrahedron Letters, 50 (2009), p. 6769-6771
[Nonpatent Document 3] S. Shvartsberg, et al., Russian Chemical Review 73(2), p. 161-184 (2004)
[Nonpatent Document 4] V. S. Romanov, et al., Russian Chemical Bulletin, International Edition, Vol. 54, No. 7, pp. 1686-1689